Solid propellant rocket motors of spherical shape



Oct. 1, 1968 P. LARUE 3,403,518

SOLID PROPELLANT POCKET MOTORS OF SPHERICAL SHAPE Original Filed July 15, 1963 United States Patent 3,403,518 SOLID PROPELLANT ROCKET MOTORS OF SPHERICAL SHAPE Pierre Larue, Chatenay-Malabry, France, assignor to Oflice National dEtudes et de Recherches Aerospatiales, Chatillon-sous-Bagneux, France, a body corporate of France Original application July 15, 1963, Ser. No. 294,832, now Patent No. 3,280,566, dated Oct. 25, 1966. Divided and this application .luly 21, 1966, Ser. No. 566,998

Claims priority, application France, July 19, 1962, 904,546, Patent 1,336,757 SClaims. (Cl. 60-253) ABSTRACT OF THE DISCLOSURE The present application is a division of my patent application Ser. No. 249,832 filed July 15, 1963, for Improvements in Solid Propellant Rocket Motors now Patent No. 3,280,566 granted Oct. 25, 1966.

The invention relates to rocket motors making use of a solid propellant, and in particular to high performance rocket motors intended to work at very high altitude, which is the case in particular of the last stage of a multistage rocket.

The present invention is concerned with such rocket motors wherein the solid propelling charge is fitted in a shell of spheroidal shape provided with a propulsion nozzle extending along a diameter of said shell.

The object of the invention is to provide a rocket motor of this type which is better adapted to meet the requirements of practice than those known up to this time.

For this purpose, according to one form of my invention, the solid propellant charge consists of two different portions both of revolution about said diameter, one of these portions being made of a propellant burning faster than that of the other, said two different portions being called the fast burning portion and the slow burning portion, respectively, said fast burning portion containing said diameter and including two diametrically opposed spherical caps, said slow burning portion surrounding said fast burning portion, and an inhibitor lining adjacent to said two propellant charge portions forms a separation between them, the surface of revolution along which said inhibitor lining extends being such that the distance from points thereof to said diameter is the smaller as said points are nearer to the center of the sphere, the spherical cap portion next to said nozzle forming the propellant ignition surface for said fast burning portion, and the part of said slow burning portion adjoining the edge of said surface forming the propellant ignition surface for said slow burning portion, said inhibitor lining being so shaped in relation with said ignition surfaces that no sliver is left at the end of the combustion of said solid propellants.

According to another form of my invention, the solid propellant charge consists of two different portions both of revolution about said diameter, one of these portions being made of a propellant burning faster than that of the other, said two different portions being called the fast burnnig portion and the slow burning portion, respectively, said fast burning portion containing said di- "ice ameter and including at its ends two spherical caps, said slow burning portion surrounding said fast burning portion and being in direct contact therewith, the surface of revolution along which said two portions are in contact With each other being such that the distance from points thereof to said diameter is the smaller as said points are nearer to the center of the sphere, the fast burning portion spherical cap next to said nozzle forming the propellant ignition surface, and the part of said slow burning portion adjoining the edge of said surface serving to the ignition of said slow burning portion, said surface of separation being so shaped in relation with said ignition surface that no sliver is left at the end of the combustion of said solid propellants.

Two preferred forms of the present invention will be hereinafter described with reference to the appended drawings, given merely by way of example, and in which:

FIG. 1 diagrammatically shows, in sectional view, a rocket motor according to one form of my invention.

FIG. 2 is a similar view of a rocket motor according to another form of my invention.

The rocket motor illustrated by FIG. 1 comprises a shell 2 of spheroidal shape, for instance of metal, provided with a nozzle 1 extending along the diameter Y-Y of said shell.

Said shell 2 contains a fast burning propellant, or powder, A, and a slow burning propellant, or powder, B, both of revolution about axis Y-Y.

The ignition area S is located on surfaces concentric with the shell and at a small distance from the surface thereof. This area is chiefly constituted by a surface consisting of a spherical cap having its axis along YY. The surface of the ignition area S located on the slow burning powder B is an annular concave zone.

The two propellants A and B are separated from each other by a lining 3 of an inhibitor substance, said inhibitor lining being so shaped in relation with said ignition surfaces that no sliver is left at the end of the combustion of propellants A and B. In the example shown, the inhibitor lining is of conical shape.

It should be noted that, in this construction, the two portions of fast burning propellant A communicate together through a small passage provided at center 0.

The rocket motor illustrated by FIG. 2 also comprises a spheroidal metal shell 2, provided with a nozzle 1 extending along a diameter YY of said shell.

Said shell 2 contains a fast burning propellant, or powder, A, and a slow burning propellant, or powder, B, both of revolution about axis Y-Y.

The ignition area S is located on the sphere that forms the external surface of the propelling charge. This area S is constituted by a spherical cap belonging to the fast burning powder having its axis in coincidence with axis YY. The portion of said ignition area made of the slow burning powder consists only of the circular line limiting said spherical cap.

The separation surface S between the two powder portions A and B is so shaped in relation to the ignition surface that no sliver is left at the end of the combustion of propellants A and B. The fast burning propellant A and the slow burning propellant B are in intimate contact with each other over the whole area of said separation surface.

It should be pointed out that it is only in the case where it is desired to obtain neutrality of the rocket motor that the diameter of the sphere must be limited to the most eccentric points of the fast burning powder portion A. If this neutrality condition were not imperative, it would be possible to increase the diameter of the sphere by providing at its periphery a concentric layer of slow burning powder.

In a general manner, while I have in the above description disclosed what I deem to be a practical and efficient embodiment of the present invention, it should be Well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the appended claims.

What I claim is:

1. A rocket motor which comprises, in combination, a shell of spherical shape, a mass of solid propellant fitting in said spherical shell, said solid propellant mass consisting of two different portions both of revolution about a diameter of said shell, one of these portions being made of a propellant burning faster than that of the other, said two different portions being called the fast burning portion and the slow burning portion, respectively, said fast burning portion containing said diameter and including two diametrically opposed spherical caps, said slow burning portion surrounding said fast burning portion, an inhibitor lining adjacent to said slow burning portion and to said fast burning portion and forming a separation between them, the surface of revolution along which said inhibitor lining extends being such that the distance from points thereof to said diameter is the smaller as said points are nearer to the center of the sphere, one of the spherical cap portions of the fast burning portion forming the propellant ignition surface for said fast burning portion, and the part of said slow burning portion adjoining the edge of said surface forming the propellant ignition surface for said slow burning portion, and nozzle means surrounding said diameter and in communication with said ignition surface, said inhibitor lining being so shaped in relation with said ignition surfaces that no sliver is left at the end of the combustion of said solid propellants.

2. A solid propellant rocket motor which comprises, in combination, a shell of spherical shape, a rearward nozzle carried by said shell and extending along a diameter thereof and a mass of solid propellant fitting in said spherical shell, said solid propellant mass consisting of at least two different portions of revolution about said diameter, one of said portions being made of a propellant burning slower than that of the remainder of said propellant mass and being called the slow burning portion, the surface of separation between said slow burning portion and the remainder of said propellant mass consisting of two opposed cones the common axis of which is said diameter, the volumes limited by said cones communicating together at the center of said shell, said slow burning portion occupying the portion of the spherical volume inside said shell between said cones, a layer of inhibitor substance forming a separation lining along said surface of separation, the end of said solid propellant mass that forms the rear surface of the rear spherical sector raving an ignition free surface located opposite said 1102- 5 11c and symmetrical about said diameter, the respective relocities of combustion of the propellants of said two Jortions being chosen, as a function of the apex angles )f each of said two opposed spherical sectors, so that no :liver is left at the end of the combustion of said solid proellant mass.

3. A solid propellant rocket motor which comprises, in ombination, a shell of spherical shape, a rearward nozle carried by said shell and extending radially therefrom nd a mass of solid propellant fitting in said spherical hell, said solid propellant mass consisting of two differnt portions both of revolution about the axis of said ozzle, one of said portions being made of a propellant urning faster than that of the other, said two different portions being called the fast burning portion and the slow burning portion, respectively, said fast burning portion, consisting of two opposed spherical sectors in contact with each other at the center of said sphere, having equal apex angles and the common axis of which is the axis of said nozzle, said slow propellant portion occupying the remainder of the spherical volume of said mass, a layer of inhibitor substance forming a separation lining along the conical surfaces of separation between said two portions, the end of said solid propellant mass that forms the rear surface of the rear spherical sect-or having an ignition free surface located opposite said nozzle and symmetrical about said axis, the respective velocities of combustion of said fast burning portion and said slow burning portion being chosen as a function of the apex angles of each of said two opposed spherical sectors so that no sliver is left at the end of the combustion of said solid propellant mass.

4. A rocket motor which comprises, in combination, a shell of spherical shape, a mass of solid propellant fitting in said spherical shell, said solid propellant mass consisting of two different portion both of revolution about a diameter of said shell, one of these portions being made of a propellant burning faster than that of the other, said two different portions being called the fast burning portion and the slow burning portion, respectively, said fast burning portion containing said diameter and including two diametrically opposed spherical caps, said slow burning portion surrounding said fast burning portion and being in direct contact therewith, the surface of revolution along which said two portions are in contact with each other being such that the distance from points thereof to said diameter is the smaller as said points are nearer to the center of the sphere, one of the spherical cap portions of the fast burning portion forming the propellant ignition surface, and the part of said slow burning portion adjoining the edge of said surface serving to the ignition of said slow burning portion, and nozzle means surrounding said diameter and in communication with said ignition surface, said surface of separation being so shaped in relation with said ignition surface that no sliver is left at the end of the combustion of said solid propellants.

5. A solid propellant rocket motor which comprises, in combination, a shell of spherical shape, a rearward nozzle carried by said shell and extending along a diameter thereof and a mass of solid propellant fitting in said spherical shell, said solid propellant mass consisting of two portions of revolution about said diameter and in direct contact therewith, one of said portions being made of a propellant burning faster than that of the other, said two portions being called the fast burning portion and the slow burning portion, respectively, the end of said solid propellant mass forming the rear surface thereof having an ignition surface in the form of a spherical cap located opposite said nozzle and symmetrical about said axis, and the surface of separation between said fast burning portion and said slow burning portion being so shaped in relation to said ignition surface that no sliver is left at the end of the combustion of said solid propellant mass.

References Cited UNITED STATES PATENTS 3,001,363 9/1961 Thibodaux et al. 39.47 XR 3,014,427 12/1961 Scurlock l02100 3,052,092 9/ 1962 Kirkbride 102-101 XR 3,073,242 l/1963 Hewson 102-101 3,120,737 2/1964 Holloway l02101 XR CARLTON R. CROYLE, Primary Examiner. 

